Subcaliber adapter



Oct. 6, 1953 J. V. DUNHAM SUBCALIBER ADAPTER Filed Nov. '7, 1949 FIG. 3.

INVEN TOR. JAMES V. DUNHAM.

ATTORNEYS.

Patented Oct. 6, 1953 UNITED STATES PATENT OFFICE (Granted under Title 35, U. S. Code (1952),

sec. 266) 4 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes Without the payment of any royalty thereon.

My invention relates broadly to subcaliber projectiles, and particularly to a means of adapting any given size of small or large caliber cartridge case to accommodate a subcaliber projectile in the form of a spherical pellet or conventional pointed bullet, missile or the like.

Recent developments in Wound ballistics (i. e. the science relating to the examination of causes and eifects, preventive measures and remedies of human Wounds caused by bullets and other iired projectiles) and other forms of research dealing with high velocity missiles have made it necessary to provide a quick, inexpensive yet efiicient means of adapting any given size cartridge case to yaccommodate a subcaliber projectile which must have an unusually high muzzle velocity when fired. My invention, which is easy to make, very inexpensive, yet highly effective, and by virtue of which the projectile is given a comparatively high muzzle velocity, is highly adaptable for use in the previously mentioned study of wound ballistics and other fields of research.

Previous to my present invention the art had known of numerous methods for adapting a cartridge case of given size to accommodate a subcaliber projectile, most of which methods had drawbacks which my development has overcome. One of the most popular prior art devices, for example, employed a removably mounted sabot o1' wood or like material mounted in the case. The sabot inclosed the projectile and was discharged from the weapons barrel along with the projectile upon nring the round. A typical example of this convention device is shown in U. S. Patent 686,375 to Wheeler wherein is disclosed a sabot that divides into fragments and becomes separated from the projectile after both leave the guns barrel. Such sabots affect the trajectory of the projectile and decrease its normal accuracy. In addition, because the sabots tend to veer in erratic, unpredictable paths away from the projectiles trajectory, a hazard is presented to personnel and equipment in the vicinity.

Another old method of adapting a cartridge case to accommodate a subcaliber projectile necessitated that a resizing operation be performed on the open end of the cartridge case. Obviously this method took much time and was quite costly because it required the use of expensive dies, tools, and machinery.

As the following description will make clear, my invention obviates the above-described disadvantages of the forerunners in its field, and at the same time possesses additional superior characteristics hitherto unknown to those experienced with the prior art.

Broadly stated, then, the object of the present invention is to provide a simple and inexpensive means for adapting cartridge cases of any given caliber to accommodate lesser caliber projectiles and make it possible to impart a comparatively high muzzle velocity to the projectile Another object is to provide `a means for adapting cartridge cases of any given caliber to accommodate lesser caliber projectiles without the need for a sabot and without the necessity of performing the conventional necking down of the cartridge case.

To obtain the foregoing and other objects and means the insert holds a projectile which is the only object shot from the firearm when the cartridge is discharged, the cylindrical insert remaining behind in the cartridge case. As earlier mentioned the projectile may be in the form of a spherical pellet or the conventional pointed bullet, missile, or the like. However, for the sake of simplicity this specication will concern the spherical pellet.

A clearer understanding of my invention will be gained from an inspection of the following type of conventional cartridge case;

Fig. 2 is a similar view of another form of my invention as applied to a second type of conventional cartridge case; and

Fig. 3 is a side View, partly in section, showing the Fig. 2 representation of my invention in position for firing Within a rearm of conventional design.

Note that Fig. 1 shows one form of my invention as applied to a cylindrical cartridge case, and that Fig. 2 shows another form of my invention as applied to a conventional necked cartridge case. Either form of my invention, however, rnay be used in either type cartridge case and, as will later be made obvious, still other embodiments of my invention may be employed in the two illustrated cases and also in many other designs of cartridge cases.

Referring to Fig. 1, in practicing my invention I provide a cylindrical plug 6 having a flat face I at one end (to the readers right) and a dished face 8 at its opposite end (to the readers left). Extending axially through the plug `is .a cylindripal opening comprising a ball chamber 9 which extends from the plugs at face 'I a substantial distance toward its dished face 8, and a smaller diametered opening IU which proceeds from the plugs dished face 8 and extends into ball chamber 9, forming the shoulder Il at the juncture therewith.

Accommodated in ball chamber` 9 and retained there by frictional resistance or other means Ais a spherical projectile I2 made of steel or other like material, the depth of the `ball chamber 9 being sufiicient to properly seat the projectile.

Cylindrical plug E is intended to be press tted, flat :face 'I outward., into the open, mouth v4.end I3 of a conventional cartridge case I4 charged with propellent powder I5 and equipped with a primer (not shown) in its head end I6. On vDressing plug 6 into place in cartridge case I4, flat face 1 of the plug is made coplanar with .the open, mouth end I3 of the cartridge case, las Fig. 1 shows. As can valso be vseen in Fig. 1, spherical projectile I2 abuts shoulder II which limits the depth of the insertion. `Projectile yI 2 also prevents escape of propellent powder I5 therepast.

In order to re the Fig. 1 cartridge, it is placed into a .suitable firearm (not shown) so that `hat face 'l of plug 6 is held rmly against a similar flat vface (not shown) .on the nrearrns barrel in order to prevent unwanted escape therepast of gas pressure resulting from ignition of propellent charge I5. The contact of these two faces acts as a ,seal to assure that the full force Aof the propellent powder will be .used only in propelling spherical projectile I2 from the rearm. Upon .ring cartridge I4, the full energy from powder charge lI5 is directed by dished face 3 of ,cylindrical plug 6 into opening ID, thence against spherical projectile I2. As a result, when the projectile moves out of 'ball chamber 9 and along the smooth bore of the rearms barrel (not shown), it is accelerated .to such va degree that by the time the projectile has reached the flrearms muzzle (not show-n) .the lprojectile has acquired a comparatively high velocity. i

`jln discussing the application `of my invention to adapting the necked cartridge case for accommodating a spherical projectile, reference will be made to Fig. 2 which illlustrates another form of -my invention.

As there shown I have provided an essentially cylindrical plug I1 consisting of .a head portion I8 `and-a neck portion I9, the two forming at their juncture a shoulder 2U. Projecting from the face 2| of head portion I8 is a boss 22 having a flat face 23. Beginning from this nat face and extending axially inward (to the readers left) through plug I1 is a central opening consisting of va cylindrical ball chamber '24 a smaller diametered cylindrical throat portion which forms at the juncture therewith a shoulder 26, and an expanding, Vfunnel-like mouth portion 21 which terminates' at the end of neck portion 'I9 of plug I1.

Accommodated in ball chamber 24 and retained there by slight frictional resistance lis a spherical projectile 28 made of steel .or other like material, the depth of the ball `chamller 24 4 being suicient to properly seat the projectile 28.

Plug I1 is intended to be press tted, neck portion I9 first, into the open, mouth end 29 of a conventional, necked cartridge case 30 having a tapered portion 3|, a head end 3'2 equipped with a primer .(not shown), .and a `charge of propellent powder 33. When plug I1 is inserted into the cartridge case 30 until shoulder 2U abuts mouth end 29 of the case, the wall of funnellike mouth portion 21 of plug I1 is substantially continuous with the inside Wall of tapered portion J3I .of cartridge case 30. As in the Fig. 1 form of my invention, spherical projectile 2l, held in place ,by slight frictional resistance, rests against shoulder 25 which limits the depth of its insertion. Projectile 28, in addition, prevents escape Aof propel-lent charge 33 out of throat portion 25 of plug I'I.

The following discussion will be devoted to describing the operation .of my novel ammuniticn, reference being made to the .Fie- 3 Showinewhich illlustrativelv depicts the Fig. 2 cartridge after it has been placed in a suitable rearm consisting of a breech 3Il, a barrel 35 having the axial opening 36 and a smooth bored liner 131 having the smooth, axial .opening 38. Examples of such firearms may be seen inl U. S. Patents 834,341 jto Tucker, 1,126,294 to Saffold, 2,342,684 to Nelson, etc. Breech 34 typically contains a chamber '.39 which accommodates my uniquely modified cartidge. Barrel 35 is threadedly attached to breech 34 at 4I), and liner 3l is secured Within barrel 3.5 (by means not shown) so that the rear faces of the barrel and of the liner are coplanar. Liner 3l carries at the readers Aleft end a recess 4I which accommodates boss y2,2 of plug il.

The firearm is loaded by uinserting the modified cartridge, neck end rst, into chamber 3S from the breech end until face 2l of head portion 18 of plug Il rests against the surface formed by the rear faces of the barrel and liner, boss 2 2 slidably tting into recess 4I in liner 31.

By conventional means such as a breech block (not shown) the cartridge case is secured into position, ready to be fired. After proper aiming, the primer (not shown) is detonated -by any conventional means (also not shown) exploding propellent charge 33 in the usual fashion. Gas pressure generated thereby is prevented lfrom leaking past the juncture of the case with the barrel by the seating o f face `2I and boss -2'2 in the firearm., and is directed by tapered portion 3l o f cartridge case 3i! and 'by funnel-like mouth portion '2 1 (see Fig. 2) against the spherical projectile.` This gas pressure forces the sphere with great velocity from chamber 24 in through bore 38 of lthe liner and out oi the nrearm.

Because of the closeness of contact between boss 22 and recess 4I, face 2| oiplug gIl and the surface formed by the coplanar rear ends of barrel 35 and its liner 31, and further 'because of the closeness lof contact between cartridge case 30 and chamber 3S in breech 34, the maximum amount o f energy derived from Aexplosion of powder 33 is used in moving the projectile toward the muzzle end of the barrel 35l From the foregoing it will be apparent that I have provided a simple and `inexpensive means for adapting cartridge cases of a given caliber to accommodate lesser caliber projectiles, which means results in imparting a comparatively high muzzle velocity to the projectile; and that I have provided a vmeans for adapting cartridge cases to accommodate lesser caliber .projectiles Without resorting to the use of a sabot and without the necessity for performing a necking down of the cartridge case.

Those skilled in the art will realize that many variations and manifestations of my invention are possible without departing from its original scope and spirit. For that reason, I do not wish to be limited to the narrow limits of the applications as here shown by way of illustration only.

I claim:

1. A subcaliber adapter for a conventional cartridge case, comprising a cylindrical plug consisting of a neck portion which is press-fitted into the mouth end of the case, a head portion protruding from the case, and a shoulder at the juncture of the head and neck portions which abuts with and seals off the open case end, said plug having therethrough an axial opening which has a smaller diameter facing the interior of the case and a larger diameter leading to the case exterior, and a ring-shaped boss projecting from said plug head portion for mating with the chamber and rear barrel end of a firearm to prevent leakage of powder gases emanating from the case past the subcaliber projectile fired through the barrel.

2. The subcaliber adapted of claim 1 in which the cylindrical plug has a funnel-shaped opening Whose narrowed mouth is confluent with the smaller diametered portion of the axial opening whereby to aid in converging the powder gases and facilitate their flow from within the case out through the plugs axial opening.

3. A cartridge having a subcaliber projectile, comprising: a conventional cartridge case; a cylindrical plug consisting of a necked portion which is press-fitted into the mouth end of the case, a head portion protruding from the case, and a shoulder at the juncture of the head and neck portions which abuts with and seals off the open case end, said plug having therethrough an axial opening; and a ring shaped boss projecting from said plug head portion for mating with the chamber and rear barrel end of a firearm to prevent leakage of powder gases emanating from the case past the subcaliber projectile fired through the barrel.

4. The cartridge of claim 3 in which the cylindrical plug has a funnel-shaped opening Whose broadest portion opens into the cartridge case and whose narrowed mouth is confluent with the rearmost portion of the plugs axial opening, whereby to aid in converging the powder gases and facilitate their now from Within the case out through the plugs axial opening.

JAMES V. DUNHAM.

References Cited in the file of this patent FOREIGN PATENTS Number Country Date 1,166 Great Britain Jan. 25, 1888 408,214 France Jan. 19, 1910 

